Most motor vehicles are equipped with bumper systems (both front and rear) intended to protect vehicle occupants against injury (and also protect the vehicle against unnecessary damage) during a crash event. By absorbing some amount of the kinetic energy of the crash, a bumper system reduces the peak deceleration of the vehicle as well as the vehicle crash intrusion, which can help to reduce the likelihood and/or severity of injury to occupants during a crash event.
A typical front bumper system includes a laterally extending bumper beam attached to the forward portion of the vehicle frame and/or body structure. Energy-absorbing components or zones are located at and/or immediately behind the bumper beam where it is supported by the frame. These energy-absorbing components or zones are generally designed to plastically deform under compression during a high-speed impact, bending or buckling in order to absorb the crash energy. In some cases, the energy-absorbing zones are provided by separate components located between the bumper beam and the vehicle. Such separately-formed components that function by energy-absorbing are often referred to as energy-absorbing cans. It is also known to provide a deformable zone integrally formed with one or more of the vehicle frame components, usually immediately adjacent to the bumper.
It is also known to provide energy-absorbing devices that employ springs, pneumatics, or hydraulics.
In a full frontal crash in which the crash loads are applied to the bumper beam in a left/right symmetrical fashion, both the left and right energy-absorbing zones are involved and able to absorb energy. In most “real world” vehicle collisions, however, the impact is offset to one side of the vehicle, in which case (depending on the amount of offset) all or most of the impact is applied to the energy-absorbing zone on the side of the crash.
One type of crash that is particularly difficult to design for is when there is a large amount of offset between the vehicle and the other object involved in the collision, so that the impact is directly on (or outboard of) the point where the bumper beam is attached to the energy-absorbing zone. In this type of event, often referred to as “small overlap” impact, only a small portion of the bumper system or frame engages the other object, so that much less of the vehicle crash energy is able to be absorbed by the bumper system and/or frame. Designing a bumper system to perform well in this type of small overlap crash is difficult, particularly since a bumper system must be effective in a range of types/modes of crashes.